112 Transactions of the Society. 



materials are derived; the spine- and aperture-scales of Euglypha 

 alveolata and E.armata are not infrequent, and tests of Nebelaequi- 

 calceus Leidy have been observed containing the body-scales of 

 Euglypha crenulqta var. minor (9). The oblong and rod-shaped 



plates so often seen in these tests usually afford no indication of 

 their origin, but occasionally close inspection will reveal traces of 

 the stria? characteristic of diatom frustules, and it is not unlikely 

 that diatoms are a source from which the necessary material is 

 largely obtained. A few species, e.g. Nehcla scutellata Wailes 

 and N. tropica Wailes (9), employ square plates in forming then- 

 tests, sometimes with the addition of about 5 p.c. to 10 p.c. of 

 circular disks, all of which are probably secreted by the animal 

 itself, unless they have been obtained from old tests of the same 

 species. A curious feature in the test of JY. scutellata is that many 

 of the points of junction of the plates are reinforced by the applica- 

 tion over them of small covering plates of suitable size and shape, 

 usually rectangular, sometimes circular, oval, or triangular (PI. Ill, 

 fig. 17). The larger plates are arranged in more or less orderly 

 diagonal series. The test of JSf. vitrcea Penard has also occasionally 

 a similar arrangement of small covering plates (PL III, tigs. 7, 8). 



Nebela barbata Leidy, recorded two or three times only from 

 the British Isles, but not uncommon in North America, is remark- 

 able for the fact that its test is thickly covered with fine, colour- 

 less, hair-like cils 10-18// in length, and less than 0*5/* in 

 diameter ; they are insoluble in cold sulphuric acid, and become 

 invisible in oil of cloves, glycerin, and balsam. 



The tests in Group 4 belong mostly to the family Euglyphina, 

 and usually consist of transparent, silicious scales or plates elliptical 

 in form, arranged more or less symmetrically, the edges overlapping 

 and cemented together. The genus Quadrula has rectangular 

 plates forming the tests, and the genus Cyphoderia is characterized 

 by the use of small disks. In all these cases the materials for 

 the test have to be secreted by the animal itself, and it is of fre- 

 quent occurrence to find individuals whose bodies enclose numbers 

 of scales, etc., ready to be used in the formation of a new test. 

 The genus Euglypha provides some of the most interesting and 

 easily procurable examples of this group, a " squeezing " from 

 any tuft of damp moss being nearly sure to provide numerous 

 specimens, of which E. ciliata Ehrenb. may serve as the type. Its 

 test is oviform or pyriform, compressed, with an elliptical aperture, 

 it is from 40 /i to 90 fx in length, and is usually furnished with 

 numerous short spines around its edge as seen in broad view ; the 

 aperture is bordered by about eight to ten scales, which have a 

 projecting point or tooth on the centre of their free edges (PI. Ill, 

 fig. 9) ; all the other scales of the test are elliptical, and arranged 

 regularly in alternating longitudinal rows ; the spines are circular 



